WASHINGTON (CNN) -- Former Bush spokesman Scott McClellan should testify under oath on Capitol Hill about his explosive new book in which he sharply criticizes his old boss, a Democratic congressman said Friday.

A book by Scott McClellan has sparked a strong backlash from his former White House colleagues.

Rep. Robert Wexler, D-Florida, said McClellan, who served as the president's press secretary before leaving the White House in 2006, would be able to provide valuable insight into a number of issues that the House Judiciary Committee is investigating.

McClellan said Friday that he would be willing to testify.

The committee is looking into the use of prewar intelligence, whether politics was behind the firing of eight U.S. attorneys in 2006 and the leaking of CIA operative Valerie Plame Wilson's identity, Wexler said.

"The administration has always called for different kinds of privileges to avoid their officials testifying, but because Mr. McClellan has put all this information in a book, these privileges, I do not believe, would be available to the administration, so we would have a free flow of information," Wexler said. Watch Wexler call for McClellan to testify »

As White House spokesman, McClellan defended Bush's policies during much of the war in Iraq, the aftermath of Hurricane Katrina and the scandal that followed the leak of Plame Wilson's identity.

He said Thursday that the latter episode was a "defining moment that caused me to become dismayed and disillusioned with the way things were going in Washington, D.C."

In the book, McClellan said he was specifically lied to about White House staff members' involvement in the leaking of Plame Wilson's identity, including former Bush adviser Karl Rove and Lewis "Scooter" Libby, Vice President Dick Cheney's former chief of staff. Watch Cheney talk about McClellan »

Libby was convicted of lying to investigators and a grand jury about his involvement in the CIA leak case. Bush commuted his sentence.

McClellan also wrote that Bush told him that he had authorized the leaking of Plame Wilson's identity to the press.

McClellan said he would would be happy to appear before Congress about how the CIA operative's identity was leaked.

"I'm glad to share my views," McClellan said. "I think I've made them very clear in the book. ... Essentially everything I know on that leak episode is written in the book -- what I was told by Karl Rove and Scooter Libby.

"When I was knowingly misled but only learned that much later, that's really when I started to become disillusioned at the White House."

McClellan's new memoir, "What Happened: Inside the Bush White House and Washington's Culture of Deception," is scheduled for publication Monday. In it he says the administration became mired in "propaganda" and political spin and played loose with the truth at times. Read excerpts from the book »

In his book, McClellan wrote that President Bush decided to go war with Iraq shortly after the September 11 attacks and then ordered his aides to make the arguments for it.

"I think very early on, a few months after September 11, he made a decision that we're going to confront Saddam Hussein, and if Hussein doesn't come fully clean, then we're going to go to war. There was really no flexibility in his approach," McClellan said on NBC's "Today" show Thursday, referring to the former Iraqi dictator. "Then it was put on the advisers: How do we go about implementing this; how do we go about doing this?" Watch a former colleague challenge McClellan's claims »

Wexler said McClellan should testify because the public has a right to know what went on behind closed doors.

"The American people deserve to know under oath what is true and what isn't [and] what this administration engaged in in terms of a conspiracy to obstruct justice," Wexler said.